Pulse commutating ring counter circuit



Nov. l1, 1952 R. B. rRousDALE A y y PULSE COMMUTTING RING COUNTER CIRCUIT Original Filed Dec. 24, 1949 FF STR/NG One Tube 0l:

0N STR/NG' ane Tube` sxnN...

INVNTOR. Robert wusdale Patented Nov. yl1, 1952 Robert fB. .Trousdald Rochester, N .fY .assignor 4:to Stromherg.-.Corlsloin Company, a :corporation of Newlork Originel'onrlieation .December- 24., 1.949, `SeriolN-o 134,974. Divided and this application April it?,

1950, "Serial No. 156,399

1K6 Claims (Cl. 3591-127) Frank .,A. :Morris .and j Robert 2B. -'Ir.ousda1e, `Serial No.. 134,974, led onlDecember :24, 19.4%. and as-r signed to the .sameossisneeas the present application. l v

, Inl many situations :it is .desirable to provide a -counter .circuit in which .driving'pulses :occurring lat iafpredetermined `repetition frate ,are counted kto:obtain ,output :pulses corresponding :to every nth driving zpulse. it Vis vfurther necessary, in some instances, .to divert or commutate @the output pulses `developed by the Vcounter .circuit suc:- cessively ,to azplurality `of electrical circuits so .as to' ..-en.er.gize .the .electrical y.circuits in a ypredeter-` minedsequence :at `tlielcounting rate ,of ,the coun.- ter circuit. A-spec'ic application of `the present invention .is in itheart of telephony, particularly in connection-Withanielectronic telephone system of thetype ,disclosed in :theabove identied appli,- cation, wherein .as systemzof multiplexing, namely., pulsed .sampling effectively atan `ail-trascina .frate of the control and. intelligence .signals produced .at .each vsubstation of the system, is :utilized Vto provide signal channel separation. `'Io-minimiz'e .the amount of equipment `used incertain com.- ponents of :the system, `e ydecimalsyst,em,of multi.- plexing 4is..femp`loyed -whichtentails arbitrary l.dirle sion of the lines .of the `system into .subrgrcups Intordercto assigne vveach line :a .particular .pulse time-position, vit isil necessary :to .count .down from a, series ,of driving pulses :which :occur v*at a rela', tivelyihigh `repetition rate toobtainuunits-anditens pulses whichmay be combinedon a.: decimal basis ato `provide 4signeil :channel separa-tion -for the lines of the system. "In such a system, it 'is necessary .tnatftliev .counter circuit '.commutateoutput pulses to various circuits during .particular ,time intere vals, otherwisethe correct sig-nal ,channelsepara- :tion snOtobtained.. 'Furthermorefit is ydesirable tofaccomplish-the,switchingactionbetweenchem nels kin a minimum amount of :.tirneso as fully to futilize the time allotted ieachchannel.

It is an object of the present :invention to pro.- yidea new..and improvedring counter, circuit `for .commutating :output-pulsessuccessively .to aplu.- f

rality fof electrical circuits.

tisnnotherlohject .offthe present .invention to f ,.2 provide a rine counter circuit :including on iinproved `starting arrangement for insuring 1.09m mutation of the counter circuit outputruloes :to

- only one output ,circuit at a time.

- occurring at a predetermined relatiivelyv ign e;

. ...pg .sus type endeten .coun stages. :or Pille :Still another object of the present invention is to provide va, pulse commutating ring counter cire cuit in which positive Vand negative output pulses `are commutated successively to a plurality -of electrical circuits `and wherein the starting of Vthe counter circuit is so arranged -as :to prevent tiple commutation from the colintr circuit tothe 4plurality of the ,electrical circuits.

It isa lfurther .object of lthe present invention tofprovide a .pulse commutatine ring counter oircuit .inwhich output pulses Yare Commutated S116.- cessively toa plurality Aof output circuits ang `.wherein the commutation period is of .extremely short duration.

vThe invention, .both as to its organization and method .of operation, together `withfurther `olo- -jects andadvantages thereof, will 1065121136 `lllllililf stood .by reference `to the following specification .taken in connection with the accornpen Lng Vdraw/ ing in which -the ,single` ligure :is ,a schein tic diagram illustrating `a pulse commutating r `counter .circuit .constructed in @CQrdance the principles of .the :present invention.

The pulse commutatingrins counter ciroutso lthe present `invention 'contemplatesv the employ.- gment of 4.two nseries of electron discharge dev interconnected toforrn a'plura'lity o f electro cs switching circuits which are operatiue in ref sponseto drivineipulses of a predetermietl Polerity' to provide Output pulses which or# a 'Summitit's.' way Lof example, the pulse commutatore ,riuscirI cuitmay ne :utilized in an electronic telephone system of the type vf lisolosed in the applietilin mentioned heretofore to .convert driving p es petition rate ,into positive :andhfgiftite tens pulses and to .divert or commutateft e tive units-or tens pulses "thus deflllQPQdsively to a series of negative lllltS @9,1 n'IlS; conductors .and `the :positive units or tens `p successively 4.to aseries of positive or pulse conductors. v i

yReferring new .more particularly tothe@ 4W- ing, there is .illustrated .anulSeQQl-'nmut g circuit,,consmioted` in accordance 'th t cpiesof the presentinvontion. i111 esterel, .the

pulse :.commutating nnecircuit :comprise .e pulse repeat-.ingenti ampli.. y' e |20- e fioriere? and gating stages, of which the rst three and tenth stages are illustrated. Each pulse gating and forming sta-ge comprises four tubes, which, for convenience of explanation, have been arranged in vertical alignment. Thus, the rst pulse forming and gating stage comprises the vertically aligned tubes |I, III, |2| and |3I, the second stage comprises the four vertically aligned tubes |02, II2, |22, and |32, the third stage comprises the four vertically aligned tubes |03, II3, |23, |33, and the last or tenth stage comprises the four vertically aligned tubes |I0, |20, |30, and |40. Considered on the basis of horizontal alignment, the tubes IOI, |02, |03, I|0, III, II2, I3, and |20 in the two upper rows are ring circuit tubes, the tubes I2I, |22, |23, and |30 inthe third row function as amplier and inverter tubes, and the tubes |3I, |32, |33, and |140 function as output tubes. All tubes included in the circuit, with the exception of the input pulse amplifying and repeating tube I0 and the output tubes |3I, |32, |33, and |40 are commercial type 6AK6 pentodes. The output tubes I3I, .|33, and |40 are commercial type 6AS7 triodes.

More specifically considered, the two top tubes of each pulse forming and gating stage are connected in the manner more fully explained be- -low to function as an Eccles-Jordan fiip-op circuit. such that the ten pairs of tubes in the two upper horizontal tube rows effectively comprise a pulse commutating ring counter circuit. The successive response of the ten Eccles-Jordan circuits to successive driving pulses developed on the ring drive conductor I I result in the production of pulses at successive stages of the ring circuit which are respectively repeated through the vcoupling condensers |50a, I50b, IBM-|507', to the control grids of the ampliiier and inverter tubes I2I, |22, I23-I30. These tubes in amplifying and inventing the pulses successively received on the control grids thereof repeat the same in amplified form through the condensers |5Ia, I5Ib, -|5|c-|5I7, successively to the control grids of the output tubes |3I, |32, I33-|-0. In responding to the pulses successively impressed upon the control grids thereof, the identified output tubes develop negative pulses successively on the negative output pulse conductors |5211, I52b, I52c |527` and simultaneously develop positive pulses successively on the positive output pulse conductors I53a, |5311, |53c--I537' in the manner generall'y explained above.

In considering the operation of the pulse commutating ring counter circuit, it is pointed out that positive driving pulses occurring at a constant frequency rate of one megacycle, for example, are applied to the control grids of the repeating device I0 and are positively repeated through the coupling capacitor I2 to the ring drive conductor II. Speciiically, each positive pulse appearing at the input terminal I3 produces a voltage drop across the resistor I0 which drives the parallel connected grids of the tube I0 positive to produce a corresponding increase in the voltage across the cathode load resistor I5 of the tube. Each time a positive pulse'is thus produced across the resistor I5, current ows through the condenser I2 and the series connected resistors I6 and I1 to increase the positive potential on the ring drive conductor II. Thus, the positive input or driving pulses to the pulse commutating ring circuit are amplified through the tube I0 and repeated to lthe ring drive conductor The input coupling condenser I8 and the output coupling condenser I2 are ofv such size as to fully discharge during each period separating successive pulses applied to the input terminal I3.

In order to start the pulse commutating ring circuit, the switch 20 is closed to bridge the voltage dropping resistor 2| and the condenser 22 in series across the terminals of the negative volts bias potential source and the positive volts anode current source in series. This operation has the effect of producing heavy current flow through the series connected elements to produce voltage drops thereacross. Initially, the major portion of the available two hundred and fifty volts supplied by the two sources appears across the resistor 2 I. However, as the condenser 22 charges up, the voltage drop across the resistor 2| is decreased to its normal Value. In this connection, it will be understood that the bypass condenser 23, which remains in the circuit and normally bypasses the resistor 2|, is of substantially smaller value than the inserted condenser 22, the resistor 2| and condenser 22 having a relatively long time constant to bring the bias voltage gradually back to its original value as the condenser 22 charges up. The transient voltage which is thus developed across the resistor 2| has the effect of shock exciting one stage of the ring circuit into operation. After operation of the ring circuit is initiated, he switch 20 may be opened and the circuit will continue to operate in the manner described below. It has been found that the described method of starting the ring circuit positively precludes the possibility of two or more stages of the circuit starting to operate simultaneously. Hence the described starting arrangement constitutes an important novel feature of the pulse commutating ring counter circuit of the present invention.

With the pulsecommutating ring circuit in operation, only one of the tubes IUI, |02, |03--I I0 in the upper horizontal string is off, i. e., nonconducting, and only a corresponding one of the tubes III, II2, ||3|20 in the second horizontal string is on, i. e., conducting at any giveninstant. Assume now that in the upper horizontal tube string, the tube |0I is not conducting with all other tubes of this string conducting and that in the second horizonal string the tube III is conducting with all other tubes of this string not conducting. With the circuit in this condition, anode current is delivered to the nine on string tubes |02, I03-IIO through the resistors |5517, I55c-I55j and the inductance elements I5b, |56c-I569` and the common voltage dropping resistor |51 from the anode current source which has a terminal voltage of one hnudred and nity volts. These impedance elements are so proportioned that the voltage drop across the resistor |51 is approximately '15 volts, which means that the anode potential on the non-conducting tube I0| is 15 volts and the anode potentials of the other tubes of the on-string are appreciably less than '15 volts.' The control grid of the off-string tube II is connected directly to the anode of the on-string tube IOI, such that when the tube IOI is not conducting the control grid of the tube I has a positive potential of 75 volts reverse impressed thereon relative to ground. However, with the off-string tube I I conducting, the current traversing this tube and the resistors I6 and I1 causes a'voltage dropl to be produced across the two identied series connected resistors which has a magnitude of approximately 15 volts. Thus the cathode of the tube I is operating at a. postive potential which 'is substantially the -i=ngpulseon the conductor II ends.

'sametas thecontrol grid potential of this tube. The bias voltage onthe controlgrid of the :tube IUI; is obviously a function ofthe voltage' drop across the resistor I59a which, in turn,v is a function of the magnitude yof current. flow .through the tube III and the series connected resistors I'f60a .and |62a. More specifically., with the tube II I conducting, the voltage drop across. the .ref sistor I50a is relatively loWi e., of the order of: 80f'volts, such that the control grid of the tube |If is negatively biased to a potential of Vapproxi-Y mately 20 volts With `respect to :the tube .cathode and the tube-.is thus biased beyond cutoff;

With the `circuit in the condition just described, the next positive drive pulse produced on .the drive pulse-conductor I I inthe mannerexplained abovehas the effect of increasing the: cathode potential of the tube III positively by fan amount suilcient to cut off space current .flow through this tube.V In response to this operation, current ilovvv vthrough the resistor' I59a .is increased to decrease the bias on the control. gridfofthe, tube .I'0I suiiicient to` render the` latter tube conduc-l tive. As the tube I 0| starts to conduct, 'its' anode becomes less positive .due .to the voltage. drop. across the inductance element IA6a and theresi'stor 15511, :with the result that al negative pulse istransmitted through the condenser `|5812 to the, control grid. of the next ori-.string tube-|02. This pulso 'is of: suicient amplitude .to drive the. control gri'dxof .the tube |02 beyond. cutoff. Asa.

consequence, `the tube |02 stops conducting and 'the anode potential thereof rises Vto increase the ositive Vpotential von the. control grid of the companion offstring tube. II2. So long as .the positive drivefpulse persists on the conductor II'to hold the cathode. potentialof the tube vI I2v at a. high. positive level, the-tube `cannot conduct even vthough the lcontrol grid potential is, positively increased .in the manner justr described.y Howevenwhen the drive pulse on the conductor I; I, ends, t he, cathode; potential of vthe tube Il 2 dropsrsuiileiently to render this tube conductive Linder the. induenoe of the inereased positive potential impressed on the control grid; of the tube from, the anode of the tube. |02. ne soonas the.. tube I I-Zf starts to conduct. the voltage drop across. theresistordb is decreased toa value such that thetube |02 remainsbiased beyond cutoff from the'negative one hundred volts bias potentiall source..` Thus, the tube |02 is held noni-.conductive after the pulse transmitted to the control grid. thereof throughy the condenserl |5811 ends.` In. this',connection,y it pointed outl that the condenser I'5`a is chosen to have a capacitance value such that the negative pulse impressed upon the vcontrol grid of the tube |02 cannot die outto render this tube conductive before the driv- This condenser isj Aalso made small enough so that it is` fully discharged before it isagain called upon to deliver-a negative pulse to the control grid of the -When the tube- I0| is rendered conductive to reduce the anode potentiall thereof in the manner-:just explained, the potential' on the control grid of# the tubeIIIf is reduced to a value-suchthat-:when- `the drive pulse on the conductor endsrthettube. III is.. still biasedfbeyond cutoif. Thus, current conduction through the tube I0| has the; effect of preventing current flow through thejtube` I;I:I'aiter` the pulse on the drive conductor I I; isterminated;

In a; manner entirely similar to. that just de scribed, the,y neri-succeeding pulse developed. on

the drive conductor I I has the effect orar-resting current conduction through. thextube I|2.,fstart.. lng `current yconduction through `the tube. 102,- arresting current conduction throughy the tube I03and starting current conduction'throughthe tube. I I3. The vmanner in which 'additional pulses appearing cnthe drive conductor I-I successively activate `the fourth to tenth stages of "thel ring circuit will be Ventirely.apparent from .the 'prefceding explanation. In `this regard, itiis noted that when the tenthpul'seiscdelivered tothe 'ring circuitfrom the drive :conductor to cut off Spade current conduction through the tube |20 and render the tube l'conductive, anegatvepillse is. Vtransmitted through the condenser- Isg'to cui; off. space.V current. flow through the .tube` I0 l, with the resultthat this tube is rendered 1norle m--` ductive andthe tube III is Vrendered conductive when the tenth drive pulse on the drive conductor II ends'.

`From Ythe above explanation, it will be'lepparent that as successive drive pulses, appear onthe drive conductor I I, the ten stagesv of thefringgfcirs cuit comprising the two upper horizontal tube strings are. sequentially activated. In order to, prevent more than one stage-of the ring-circuit from. responding to anyeiven. drive pulse. the resistors 'fiend Il are so proportioned thatsfif two of the oit-string tubes III, IU-|20 start, to.

conduct simultaneously a; voltage drop is pro-H duced across these. resistors. which has the efeot of biasing both of the conductingtubes beyond. cutoff- As a practical matter.. this is.socorriplished by adjustingV theshort-eirouitins wiper Ila along` the resistor I'I-to a point where rent flow through. any one of the tubes l .1. II2-,-I20 and the resistors I 6 and I-I has-the .ete feet of biasing these tubes fairly close to thernitoff point.. It will beimderstood that. with the oireuit adjusted in this manner... positive drive pulses of relatively lovv amplitude, appearing en the drive conductor II will have the @liet switching the ring circuit. the manner einV plained above. -V

Another important yfeature of the pulsecom.- mutating ring counter circuit of the presenttin-.e vention is thev use of coupling condensersv 158e.V |581?, I58c-I587' connected between theanodes. and control grids of` successive. tubes, I0,I, IM, I0 3-I I0 of theon-string rather than. between successive tubes III, ||2,` II3-.I20 of the'otfe string. This arrangement is of importance.; for the reason that since the tubes of they off-.string are normally biased considerably beyond cutoff arelatively large, changein the. potentials ori-the, control grids thereof would be required to. effect the described stage switching operations in response to delivery of successive drive pulses to, the pulse commutating ring circuit. On the other hand,v the control grids of the on-string,v tubes IDI, |02, I03I I0 are normally biased to satura, tion through the resistors I59a, |592), |,59cf-.If50j-i As a consequence, delivery of a small negative pulse` to the control grid of any on-string tube,`

as to the control gridofthe tube I02throughthecondenser |58a, for example, has: theA effectief;

cutting off space current flow 'throughy the. tube.

In considering the manner in which the Step.- by-step operation ofthe'pulse commutatingfring circuit results intheproduction of positive; and negative output pulses successivelyon the nega:d tive output pulse conductors I 52 and thefpositive output pulse conductors |53, it is. iirst pointed out that normally the amplifierV and. inverter tubes I2I1, |222, IMP-.|30 are conducting heavilir;

Thus, the control grids of these tubes are respectively connected through the grid current limiting resistors |64a, |541), Hide-|647' directly to the positive terminal of the anode current source, so that heavy grid and anode currents flow in these tubes. On the other hand, the tubes |3|, |32, ISS-|40, constituting the output string, are normally biased beyond cutoff by the charges accumulated on the respective associated condensers ||a, |5|b, |5|c-|5|:i.

With the pulse commutating ring circuit operating in the manner described above, negative pulses are developed on the negative output pulse output pulses are developed on the positive pulse conductors |530., |531), |53c|53i only When the respective corresponding tubes H2, IIS-| are conducting. Thus, a negative pulse is developed on the negative output pulse lead |52a and a positive pulse is developed on the positive pulse lead |53a when the tube is rendered conductive under the influence of a driving pulse on the conductor More specifically, when the tube is rendered conductive to produce space current ow therethrough, the positive potential of its anode is decreased to transmit a negative pulse through the coupling condenser |5011, to the control grid of the tube |2|. This pulse, during its persistence interval, has the effect of decreasing space current ow through the tube |2| to produce a corresponding increase in the positive anode potential of the tube. As a result, the pulse is inverted to a positive pulse and repeated in amplied form through the con-'- denser |5|a to the control grid of the output tube |3|. This repeated positive pulse is of very large amplitude and has the effect of driving the control grid of the tube |3| sufficiently positive to saturate space current flow through the tube. Thus, the tube |3|, which as explained above is normally cut off, is abruptly rendered conductive at its saturation level. During the conducting interval of the tube |3|, the condenser |5|a is heavily charged by grid current ow through this tube, such current ow occurring over a path which extends from positive terminal of the anode current source by Way of the resistor |65a, the inductance element |36a,

the condenser |5|a, the grid-cathode path in' the tube |3|, and the resistor |i la to the grounded negative terminal of the anode current source. As a result of the heavy anode current flow thus produced through the tube |3|, the voltage drop across the cathode resistor Ilia is sharply in- .vcreased to produce the desired positive pulse on. the positive output pulse conductor |53a. Concurrently therewith, the voltage drop across the anode load resistor Ila is sharply increased to correspondingly decrease the potential on the negative output pulse conductor |52a and thus develop the desired negative pulse on this conductor.

The duration of the pulses thus developed on the output pulse conductors |52 and |53 is measured by the spacing interval between two successive drive pulses appearing on the ring drive conductor Il. Thus when the next succeeding drive pulse is developed on this conductor to render the tube non-conductive in the manner explained above, the positive anode potential of this tube is sharply increased to produce a corresponding sharp increase in current iiow through the tube |2|. As a result, the positive anode potential of the tube |2| is sharply decreased. More specifically, the voltage at the anode of the tube |2| is less than the voltage across the condenser I5|a, which is now nega-.,- tively applied to the control grid of the tube |3|, by an amount suiiicient to cut off space current flow through the latter tube. As a consequence, the voltage drops across the resistors Illa. and |'|0a are sharply decreased to their reference value levels to terminate the pulses on the conductors |53a and |52a.

In a manner entirely similar to that just described, negative and positive output pulses are respectively produced on the conductors |5211 and |5311 in the next succeeding time position during successive intervals of conduction of the tube ||2. Similarly, positive and negative pulses are respectively produced on the conductors |53c and |52c in the next succeeding time position during those intervals when the tube ||3 is conducting. Thus it will be understood that negative output pulses are successively produced on the conductors |52a, |5212, |52c|52i and positive output pulses are concurrently produced on the conductors |53a, |5311, |53c|531i in the manner described during sustained operation of thel pulse commutating ring circuit.

As will be apparent from the preceding explanation, the output pulses produced by each of the tubes |3|, |32. |33|40 are developed by switching each tube from a completely non-conductive state to a condition where anode current iiow through the tube is at the saturation level.

This insures the production of output pulses of uniform amplitude having clean tops. As will also be apparent from the preceding explanation, each of the coupling condensers |50a, |501), ISOC-|507' is only required to hold the control grid potential of the associated one of the tubes |2|, |22, |23|30 at the pulse producing level for an interval equal to the period separating two successive pulses on the drive conductor Accordingly, these condensers may be relatively small. During the interval separating pulse transmission by each of these condensers and equal to the sum of nine output pulse periods. each condenser is fully discharged through one of the respective associated resistors |64a, |64b, Imc-|6471 On the other hand, each of the condensers |5|a, |5|b, |5|c|5|i is required to hold itsA charge during each spacing interval separating two pulse transmission periods thereof, i. e., during intervals each equal to the sum of nine units pulse periods. Accordingly, these condensers are relatively large. During such spacing intervals these condensers discharge through their respective associated resistors IB'Ia, |611), M570-461i. However, these resistors have very high resistance values such that the condenser discharge rate is low. The inductance elements, such as the elements |56a, |6|a and |66a respectively provided in the anode circuits of the tubes forming the upper three rows serve the function of preventing width distortion of the pulses. Each of these elements is self-resonant at a frequency of four to rive megacycles.

By way of example, and not in any sense as a limitation to the particular values given, a pulse commutating ring counter-circuit constructed in accordance with the present invention, when sup-l plied with one megacycle driving pulses of positive polarity has been found satisfactory successively to commutate to ten individual output circuits, positive and negative output pulses occurring at a frequency of kilocycles, i. e., a counting rate of ten to one, and having a. duration approximately' equal to.` the spacing between; driviifng pulses', i..l e.,:: one micrcsecond..

f Irrthe speciiicy embodiment other-circuit constants employed yare as follows:

Resistor i4 Lxnego'hm Resistor |5 4700 ohms Resistor I6 3300 ohms Resistor t1 1000 ohms4 Resistor 2l 1000 ohms Resistorl l`55a l3900 ohms ,Resistor |51'. 150 ohms Resistor |5906. 33,000 ohms Resistor I60a`. 3900'ohms Resistor [62a 56,000 ohms Resistor |6411 150,000 ohms Resistor-'16M'. 3900 ohms Resistor |6111. 1 megohm Capacitor |'2 1000 mmf. Capacitor i8 1000 mmf.. Capacitor 22 30 mfd. Capacitor 23` .1; mid. Capacitor lilla". 1.00 mmf. Capacitor I 5Ia' 500 mmf` Capacitor [5811'. 5 mmf. 'Capacitor |630 10 mmf. l

'Itfwill be understood thatthe circuit constants ofthe second' through tenth stages'of theA pulse cox'nmutatingring circuit are identical with the values` given above.

" Whileu there has been described what isI vat present' considered to bef the preferred embodiment of the inventionI it will be understood that various modiiicationsA may be'made therein which ``a're -'within thev true spirit andscope of the in- *vention as dened inthe appended claims. {`=""'What is claimed asy new and is desired' to be secured by Letters Patent-of' the UnitedStates is:

l-l pulse commutatingring counter circuit,

'comprising a pluralityv of'velectronic switching circuits, `means connecting` said circuits in'y an 'endless series', an impedance common to all` of jsaidcircuitsy and included' in the. space current pathof each of said circuits, a source of driving pulses, means connecting said source toV said impedance thereby' sequentially vto actuate' said switch-ing circuits in. accordance with said drivingjfpulses-and means for deriving anoutpuwt Apulse from eachfof said switching' circuits in acn accordance with successive actuations' thereof',

and starting means for conditioning said switching' circuits" for subsequent actuation by said driving pulses.

3;-A A 'pulse commutating ring counter circuit, comprising a plurality of electronic switching circuits, means. connecting said circuits in an endless'series, an impedance common to allA of said circuits, a source of driving pulses, means connecting said source to said impedance thereby' tov actuate said switching circuits in prede- Ytermined sequence in accordance' with said driving. pulses., means for deriving output. pulses' from circuits in predetermined. sequence in accordance with` said driving pulses. means for'deriving output pulses from each of said switching circuits in accordance with successive actuations thereof, said common impedance having a value large enough. substantially' to prevent, multiple lactuation of saidy switching circuits whilel permitting actuationy of ay single one of said circuits in response to said drivingpulses.

5. .A pulse.l commutating ring. counter circuit, comprising a plurality of electronic switching circuits, means including a` plurality of networks for connecting said circuits inv an endless series, an impedance common to all of said circuits, a sourcer of driving pulses, means connecting said source to said impedance thereby sequentially to actuate said switching circuits in response to said, driving pulses, and meansr for deriving an output pulse from. each of: said. switching circuits in accordance with successive actuations thereof each of said plurality ofnetworks `having a time constant long. as? comparedtol the duration of said driving pulses and shoiftl as.` compared to the period between: successive actuations ofi 'any one of said circuits.V

6. Av pulse commutating ring counter circuit, comprising a plurality of electronic switching circuits,; means: connecting said. circuits in an endlesszseries, an impedance: common` to all of said circuits, a source of driving pulses, means connecting said source to said impedance thereby to actuate said switching circuits in` predetermined. sequence in response to said driving pulses, a phase inverting stage for each of: said circuits, means for including a rst network having a time constant short as compared to. the period between successive actuations of a given circuit for coupling each of said circuits to the associated vphase -inverter stage, an: output stage for each of said: phase inverter stages, and means including a` second network `having a time constant long as. compared to said actuationy interval 'for coupling each of said phase.` inverterl stages to the associatedl output` stage, and means'v for deriving positive and negative output pulses` from each of said. outputv stages.

7.. A pulse 'commutating ring counter circuit, comprising iirst and second equal numbered series of electron discharge devices, a source of driving pulses, means connecting kthe anode of -each device, in said rst series to the control electrode of the next succeeding device in said v`ilrst series, means for connecting the anode of 'each device in said first series tothe control electrode of the corresponding device in said second series, means connecting the control elec'- trode ofr each device in said i'lrst -series to the anode of the corresponding device in said sec- Y ond series andA to a source of negative potential, means connecting the cathode of each ofsaid devices in said lsecond series to a common im# 'pedance, means connecting said source of driving pulses to said common impedance, and means for deriving a commutated output pulse from each device in said second series.

8. A pulse commutating ring counter circuit comprising a first series of electron discharge devices, a source of driving pulses, a second series of electron discharge devices equal in number to the devices in said rst series, means including resistance means for connecting the anode of each device in said first series to the control electrode of the corresponding device in said second series, means directly connecting the anode of each device in said second series to vthe control electrode of the corresponding denecting the anode of each device in said second series to the control electrode of the next succeeding device in said second series, means for deriving a commutating output pulse from each tube 'in said first series, and means for starting said iirst and second series of tubes in a predetermined sequence.

9. A pulse oommutating ring counter circuit comprising a rst series of electron discharge devices, a source of driving pulses, a second series of electron discharge devices equal in number to the devices in said rst series, means including resistance means for connecting the anode of each device in said rst series to the control electrode of the corresponding device 1i. said second series, means directly connecting th'U anode of each device in said second series to the control electrode of the corresponding device in said iirst series, means connecting the control electrode of each device in said first series to a negative source of potential, means connecting the cathodes of all the devices in said first series 'to a common impedance, means connecting the anode of each device in said second series to the control electrode of the next succeeding device in said second series, means for deriving a commutated output pulse from each device in said rst series, and means for starting said series l of devices in a predetermined sequence, said last named means including means for reducing the valueu of said source of negative potential.

l0. A pulse commutating system, comprising a source of driving pulses and a series of electronic switching stages, each of said stages comprising iirst and second electron discharge devices, means f,

trode of said first device, means connecting the control electrode of said rst -device to a negative source of potential, means connecting the cathode of said second device to said source of driving pulses, means for deriving an output pulse from the anode of said second device, and means connecting the anode of said rst device to the control electrode of Ithe rst device of the next succeeding switching stage thereby to cause said driving pulses successively to actuate said series of switching stages.

1l. A pulse commutating system, comprising a series of counter stages, each of said stages comprising an electronic switching circuit a phase inverter stage and an output stage, means including a rst network for connecting said switch- I12 ing circuit to said phase inverter stage. means including a second network for connecting said phase inverter stage to said output stage, an impedance common to all said switching circuits, means for supplying driving pulses to said common impedance, and means for connecting the switching circuits of said stages in an endless series thereby to cause said driving pulses successively to actuate said series connected switching circuits, said iirst networks having time constants short as compared with the period between successive actuations of a given switching circuit, and said second networks having time constants long as compared to said actuation interval.

12. A pulse commutating system, comprising a source of driving pulses and a series of electronic switching stages, each of said stages comprising rst and second electron discharge devices, means directly connecting the anode of said rst device to the control electrode of said second device, means including a resistor for connecting the anode of said second device to the control electrode of said first device, means connecting the control electrode of said first device to a. negative source of potential, means connecting the cathode of said second device to said source of driving pulses, means for deriving an output pulse from the anode of said second device, and means connecting the anode of said rst device to the control electrode of the rst device of the next succeeding switching stage, and means for starting said pulse commutating system, said last named means including means for decreasing the potential of said negative potential source.

13. A pulse commutating ring counter circuit. comprising a plurality of electronic switching tubes, means connecting said tubes in an endless series, an impedance common to all of said tubes and included in the space current path of each of said tubes, a source of driving pulses, means connecting said source to said impedance, thereby sequentially to render conductive said switching tubes at the rate of one tube for each driving pulse, and means for deriving output pulses from said switching tubes as said tubes are sequentially rendered conductive.

14. A pulse commutating ring counter circuit, comprising a plurality of electronic switching tubes, means connecting said tubes in an endless series, an impedance common to all of said tubes and included in the space current path of each of said tubes, a source of driving pulses, means connecting said source to said impedance, thereby sequentially to render conductive said switching Vtubes at the rate of one tube for each driving pulse, and means for deriving an output pulse from each of said switching tubes as said tubes are sequentially rendered conductive, said common impedance having a value large enough substantially to prevent multiple conduction of said switching tubes while permitting conduction of a single one of said tubes in response to each driving pulse.

l5. A pulse commutating ring counter circuit. comprising a plurality of electronic switching tubes, means connecting 'said tubes in an endless series, an impedance common to all of said tubes and included in the space current path of each of said tubes, a source of driving pulses of positive polarity, means connecting said source to said impedance, means responsive to pulses produced across said impedance by said source for rendering all cf said tubes non-conductive-for the duration of each driving pulse, means responsive to' cessation of each of said driving pulses for sequentially rendering said tubes conductive at the rate of one tube for each driving pulse, and means for deriving an output pulse from each of said switching tubes during each period when the tube is rendered conductive.

16. A pulse commutating ring counter circuit, comprising a plurality of electronic switching tubes, means connecting said tubes in an endless series, an impedance common to all of said tubes and connected to the cathode of each of said tubes, a source of driving pulses of positive polarity, means connecting said source to said impedance, means responsive to pulses produced across said impedance by said source for rendering all of said tubes non-conductive for the duration of each driving pulse, means responsive to cessation of each of said driving pulses for se- 14 quentially rendering said tubes conductive at the rateof one tube for each driving pulse, and means for deriving an output pulse from each of said switching tubes during each period when the tube is rendered conductive.

ROBERT B. TROUSDALE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,272,070 Reeves Feb. 3, 1942 2,306,386 Hollywood Dec. 29, 1942 2,402,432 Mumma June 18, 1946 2,426,454 Johnson Aug. 26, 1947 2,443,198 Sallach June 15, 1948 

